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Challenges of managing anomalous mitral arcade with severe mitral regurgitation and hydrops fetalis in infants
  1. Tienake Trisauvapak,
  2. Nitiroj Bongkotwilawan and
  3. Suparat Ekawaravong
  1. Pediatrics, Chakri Naruebodindra Medical Institute, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Samut Prakan, Bang phli, Thailand
  1. Correspondence to Suparat Ekawaravong; suparatekawaravong{at}gmail.com

Abstract

Anomalous mitral arcade (MA) is a rare congenital anomaly. We report a case of MA in a newborn who presented with hydrops fetalis due to severe mitral regurgitation. After birth, he developed severe respiratory failure, congestive heart failure and airway obstruction because an enlarged left atrium from severe mitral regurgitation compressed the distal left main bronchus. There is limited experience in surgical management of this condition in Thailand, and the patient’s mitral valve was too small for replacement. Therefore, he was treated with medication to control heart failure and supported with positive pressure ventilation to promote growth. We have followed the patient until the current time of writing this report at the age of 2 years, and his outcome is favourable regarding heart failure symptoms, airway obstruction, growth and development. This case describes a challenging experience in the non-surgical management of MA with severe regurgitation, which presented at birth.

  • Heart failure
  • Nutritional support
  • Congenital disorders
  • Cardiothoracic surgery
  • Valvar diseases
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Background

Anomalous mitral arcade (MA), also known as hammock mitral valve (MV), is a rare congenital malformation of the MV and its associated tensor apparatus. Infants diagnosed with this condition often present with symptoms of congestive heart failure (CHF) due to severe mitral insufficiency, mitral stenosis (MS) or both. Limited data are available on the medical management of this condition, and surgical repair in this age group is technically challenging. Reports on surgical outcomes of MA are variable, with limited experience in performing the procedure. As a result, decision-making and care for infants with MA pose considerable challenges. In this report, we present a case of hydrops fetalis caused by severe mitral regurgitation (MR) resulting from MA. The patient achieved favourable outcomes in medical management, benefiting from a holistic treatment team. Additionally, we conducted a literature review on the medical management, associated complications and surgical data to aid in decision-making regarding this condition.

Case presentation

A term male newborn with a gestational age of 38 weeks and a weight of 3800 g presented with severe respiratory distress immediately after birth. He was transferred to the neonatal intensive care unit and required endotracheal intubation for ventilatory support. On a physical examination, tachycardia, tachypnea, generalised oedema and hepatomegaly were observed. A grade IV/VI pansystolic murmur was heard at the apex with an active precordium. A chest X-ray revealed marked cardiomegaly (figure 1). An ECG showed sinus rhythm with evidence of left atrial (LA) enlargement. Transthoracic echocardiography revealed severe enlargement of the LA and left ventricle (LV), moderate tricuspid regurgitation (estimated tricuspid regurgitation pressure gradient of 50 mm Hg), severe MR, absence of MS and a small amount of pericardial effusion. The LV ejection fraction was 66%. The apical four-chamber view on echocardiography showed short thickened cords and enlarged elongated papillary muscles in direct continuity with the anterior and posterior MV leaflets (figure 2). In addition, a column of fibrous tissue forming an arcade extending between the papillary muscles was observed in the apical four-chamber and parasternal short-axis view (figure 3). The MV annulus measured 14 mm in diameter. A central coaptation gap between the anterior mitral valve leaflets (AML) and posterior mitral valve leaflets (PML) was noted due to the restrictive valvular motion, resulting in severe MR (figure 4A and B). The large MR jet flow occupied nearly the entire LA area and was directed towards the pulmonary vein (figure 4C). A diagnosis of MA with severe regurgitation with pulmonary hypertension was made. The patient received dobutamine, furosemide and spironolactone while receiving full ventilatory support. Additionally, fluid intake was restricted, and efforts were made to achieve a negative fluid balance. We discussed the risks and benefits of mitral valve replacement (MVR) with the cardiovascular team. Due to a lack of experience with MA repair in infants at our institute and the patient’s MV being too small for replacement, we concluded that supportive care for further growth would be the best course of action. After 1 week, the patient’s CHF was under control. A follow-up chest X-ray revealed a decrease in cardiac size. However, LA enlargement was still observed, as indicated by a double contour sign, along with mild pulmonary venous congestion (figure 5). Echocardiography showed that MR had decreased to a moderate degree, with slight improvement in LA and LV enlargement. Pulmonary hypertension had improved, as demonstrated by a decrease in the tricuspid regurgitation pressure gradient to 25 mm Hg. The patient was weaned off the ventilator and subsequently extubated. The medication regimen was switched to oral digoxin, furosemide and hydralazine.

Figure 1

(A) chest X-ray shows considerable cardiomegaly after birth.

Figure 2

(A, B, C, D, E and F) Echo imaging shows absent or short thickened cords (red asterisk), enlarged and elongated papillary muscles (PM) in direct continuity with the anterior mitral valve leaflet (AML) and posterior mitral valve leaflet (PML) (yellow dotted arrows). *Readers can compare the described findings with the illustrated picture (figure 9).

Figure 3

Echo imaging shows a column of fibrous tissue forming an arcade extending between the papillary muscles (PM) (red arrow) in (A, B) the apical four-chamber view and (C, D) the parasternal short-axis view. Abbreviation: MV, mitral valve. *Readers can compare the described findings with the illustrated picture (figure 9).

Figure 4

(A) The apical four-chamber view shows a central coaptation gap (red arrow) and severe mitral regurgitation (MR). (B) The parasternal short-axis view shows a posterior large MR jet from the coaptation gap between the AML and PML (red arrow). (C) The subcostal view shows a large MR jet area in the left atrium, directing towards the pulmonary vein. Abbreviations: LA, left atrium; LV, left ventricle; LVOT, left ventricular outflow tract; AML, anterior mitral valve leaflets; PML, posterior mitral valve leaflets; PV, pulmonary vein.

Figure 5

One week after CHF treatment, a chest X-ray shows reduced cardiac size and left atrial enlargement was still observed, as indicated by the double contour sign (red dashed line). CHF, congestive heart failure.

One day after the patient’s extubation, he developed progressive tachypnea. A physical examination showed inspiratory and expiratory rhonchi in the left lung with subcostal retraction. A CT scan of the airway was performed to evaluate airway obstruction, revealing LA enlargement measuring 2.6×3.3 cm in the maximum transaxial diameter. This atrial enlargement caused a pressure effect on the distal left main bronchus, resulting in segmental luminal narrowing, with the narrowest diameter being approximately 2 mm (figure 6). The patient was supported with continuous positive airway pressure to maintain airway patency. On the 16th day of life, he developed bloody stool following fortifying high-calorically dense formula. Pneumatosis intestinalis was observed in an abdominal radiograph, confirming stage IIa necrotising enterocolitis. Nil per os, parenteral nutrition and intravenous antibiotics were required. Subsequently, on the 24th day of life, trophic feeding was initiated using breast milk and gradually increased. However, due to poor weight gain with fluid restriction and inadequate breast milk supply, a switch to high-calorically dense formula was implemented to achieve an energy intake of 130 kcal/kg/day and a protein intake of 2.7 g/kg/day via the oral route. Additionally, multivitamin, iron and zinc supplementation were provided. The airway obstruction improved after CHF was well controlled, and the patient was able to be weaned off continuous positive airway pressure. At the age of 2 months, he was discharged from hospital with a weight of 4035 g.

Figure 6

CT of the airway shows segmental luminal narrowing of the distal left main bronchus.

The patient was followed up by a paediatric cardiologist, paediatrician nutrition specialist and a newborn team. At 3 months of age, he experienced frequent postprandial regurgitation and non-bilious vomiting, and exhibited a suboptimal growth rate. Gastro-oesophageal reflux disease was diagnosed, and management included maintaining a head elevation position during feeding and administering lansoprazole. Furthermore, energy intake was adjusted to 140–150 kcal/kg/day along with a protein intake of 2.5–3.2 g/kg/day by fortifying a high-calorically dense formula with maltodextrin, long-chain triglycerides and medium-chain triglycerides. After this treatment, his reflux symptoms were ameliorated, leading to discontinuation of lansoprazole. At 11 months of age, he showed catch-up growth (figure 7) with age-appropriate feeding practices and normal development. At 18 months of age, an echocardiogram showed a considerable improvement in MR, with a decrease in the LA volume index from 92.9 mL/m2 (figure 8A) to 47.2 mL/m2 (figure 8B,C). His condition is currently controlled with a low dose of furosemide and spironolactone.

Figure 7

Pattern of growth in this patient from birth to 18 months of age (the figure was created by Nitiroj Bongkotwilawan).

Figure 8

Left atrial volume at (A) 3 days of age compared with (B) 18 months of age. (C) MR is reduced to a mild degree at 18 months of age. MR, mitral regurgitation.

I

Outcome and follow-up

We have followed the patient until the current time of writing this report at the age of 2 years, and his outcome is favourable regarding heart failure symptoms, airway obstruction, growth and development. The patient has follow-up appointments with a paediatric cardiologist and paediatric nutritionist every 3–6 months.

Discussion

Anomalous MA or hammock MV is a rare congenital malformation of the MV that was first described by Layman and Edwards in 1967.1 Anomalous MA is thought to result from arrested embryonic development of the MV before lengthening and attenuation of the chordae tendineae.2 The cardinal morphological features of MA include an absent or short chordae tendinae, interconnecting band of fibrous tissue between two papillary muscles (fibrous bridge) and elongated papillary muscles with direct attachment to mitral leaflets (figure 9).3 The lack of interposition of chordae between the fibrous bridge and mitral leaflets creates a fibrous continuity that restricts valvular motion and prevents the apposition of normal leaflets, leading to valvular insufficiency.4 CHF symptoms can occur in individuals of various age groups, depending on the severity of valvular insufficiency or stenosis.

Figure 9

Illustrates the cardinal morphological features of the mitral arcade: absent or short chordae tendineae, interconnecting band of fibrous tissue between two papillary muscles (PM), and elongated PM. It also shows the direct attachment of PM to the mitral leaflet (white arrow) and a view from the left atrium (inset). (Reproduced with permission from: Hakim FA, Krishnaswamy C, Mookadam F. Mitral arcade in adults—a systematic overview. Echocardiography 2013;30:354–9).

There have been several case reports in which MA was found in association with cardiac lesions, such as aortic stenosis, coarctation of the aorta, pulmonary stenosis, ventricular septal defect and total anomalous pulmonary venous connection (table 1). Additionally, a few case reports have described patients with MA who presented with rare associated cardiac lesions. Two case reports showed a concomitant anomalous left coronary artery from the pulmonary artery,5 6 and another case report showed a concomitant aorticopulmonary window.7 Another study showed an association between MA and twin–twin transfusion syndrome based on autopsy results.8 In 4 of 11 (36%) recipient twins, MA was identified, and 2 cases showed hydrops on obstetric ultrasound. Fetal hydrops can be caused by severe MR, LA enlargement and LA hypertension.

Table 1

Review of the literature on paediatric patients with mitral arcade

Echocardiography was a highly effective modality in identifying the anomaly in this case. However, notably, relying solely on a single imaging plane may hinder the comprehensive evaluation of MV apparatus anomalies and associated functional disturbances. To achieve a more detailed assessment, the incorporation of three-dimensional echocardiography and cardiac MRI could be considered as additional options during infancy.9 Recent studies have highlighted the potential benefits of combining three-dimensional transoesophageal echocardiography with multidetector CT, which can enhance spatial resolution and facilitate arcade reconstruction. This approach enables a more precise diagnosis and improved guidance for surgical management in adults.1 4

Medical management of MA aims to control CHF due to MV insufficiency. The degree of MR from MA may be combined with secondary MR owing to LV dilation, LA enlargement and mitral annular dilatation, which secondarily increases the leaflet coaptation gap. In addition, LV systolic dysfunction reduces the strength of closing the MV, opposing the leaflet tethering forces created by papillary muscle displacement.10 A reduction in preload might result in a reduction in functional MR due to a decrease in the LA and mitral annular size.11 In patients with MR, forward cardiac output decreases with the onset of decompensation. A reduction in systemic vascular resistance increases forward cardiac output and reduces the regurgitation volume, thus being beneficial in the management of such patients. Several studies have shown that intravenous dobutamine infusion effectively increases the mean forward stroke volume, while decreasing LV end-diastolic volume, LV end-systolic volume and the coaptation gap of MV leaflets, resulting in a decrease in MR.12–14 Studies on vasodilator therapy in children are limited. One study showed that nitroprusside and hydralazine increased the cardiac index and stroke volume index in children with LV dysfunction or MR.15 Angiotensin-converting enzyme inhibitors may be used for afterload reduction in adults, but there are little data available for infants.16

Generally, pulmonary artery pressure decreases dramatically after birth,17 but this may not be the case in situations of severe MR. Post-capillary pulmonary hypertension, resulting from an increase in LA pressure as a consequence of severe MR, may lead to an elevation in pulmonary vascular resistance.18 In our case, pulmonary hypertension resolved after effectively managing CHF with controlled MR.

Although congenital cardiac defects are infrequently considered a cause of major airway compression in neonates and infants, patients with severe MR leading to marked LA dilatation may develop airway compression.19 The LA is situated adjacent to the carina and can directly compress the distal trachea and main stem bronchi, as well as widen the angle of the tracheal bifurcation.20 When there is an increase in the mean pulmonary arterial pressure, mean LA pressure and the carinal angle, the combined enlargement of the pulmonary artery and LA can result in compression of the left bronchus.19–21 Furthermore, marked enlargement of the LA can increase the risk of atrial fibrillation and the formation of thrombus. This complication should be monitored in these patients.22 23

MA is the most difficult MV anomaly to correct because the subvalvular apparatus is challenging to expose.2 The timing of surgery is ideally postponed to allow time for annular growth and tissue maturity. This postponement is usually considered to be safe because depressed systolic ventricular function has been shown to recover after successful MV surgery in paediatric patients.24 25 However, in cases of severe CHF refractory to maximal medical therapy, surgery during infancy may be necessary. The decision regarding the best surgical strategy is particularly challenging. We reviewed the literature on surgical procedures and outcomes in cases of MA during infancy, including retrospective studies and case reports spanning from 1995 to 2023 (table 1). The surgical decision was based on the experience of each institution, and the reported outcomes varied. Primary MV repair during infancy is a major high-risk factor for death or transplantation, and is associated with a high rate of recurrence and early reintervention.26 27 One study showed that MA was a strong predictor for a poor outcome after primary repair.28 MVR may be considered according to the assessment of risks and benefits. The serious disadvantages of MVR in a growing child include patient–prosthesis mismatch, requiring serial valve replacements, and obligatory lifelong anticoagulation therapy.29 Mechanical prosthetic valves are only available down to a size of 15 mm.29 A recent multicentre study examined early and mid-term outcomes using 15 to 17 mm prosthetic MVR in 61 infants between 1998 and 2018.30 This previous study reported 13 (21%) in-hospital deaths and 8 (17%) late deaths. Additionally, major adverse events were observed in 34 (56%) infants. In the median follow-up period, the first prosthetic valve replacement occurred at a median of age of 3.7 years. Furthermore, 9 (15%) infants required other reinterventions, including permanent pacemaker implantation.30 In cases where the annulus is hypoplastic, measuring less than 15 mm, accepting a mechanical prosthetic valve is not appropriate. As an alternative approach, other adaptive techniques using off-label and modified surgical mitral bioprosthetic valves have been used, such as the Melody valve, which involves using a bovine jugular venous valve mounted inside a stent or GoreTex tube graft.31 32 However, owing to the limited number of cases in individual centres, there have been few reported outcomes.

Malnutrition is prevalent in patients with congenital heart disease.33–35 Congenital heart disease is associated with unfavourable clinical outcomes, such as increased infectious complications, prolonged mechanical ventilation, an extended hospital stay, elevated hospital mortality36–38 and impaired neurological development.39 40 The aetiology of malnutrition in CHF is multifactorial, involving increased energy requirements, inadequate intake, nutrient losses from gastro-oesophageal reflux disease or intestinal malabsorption, and fluid restriction.41 42 Oral or enteral feeding is beneficial and should be considered when haemodynamic variables are stable, while parenteral nutrition should be considered when enteral nutrition is not feasible or insufficient. To prevent catabolism and promote growth in infants with CHF, an additional energy intake of approximately 120–150 kcal/kg/day and protein contributing 8%–12% of total calories is necessary. However, protein should be limited to 3.5 g/kg/day to prevent excessive hepatic protein metabolic and renal solute load.41 43 In cases of restricted volume, concentrated feed through fortification of human milk or concentrated formula improves energy intake and weight gain with good tolerabiltiy.44–47 Additionally, in patients with congenital heart disease, particularly those receiving diuretic therapy, electrolytes and micronutrients, such as potassium, calcium, magnesium, zinc, iron and thiamine, may be depleted. Therefore, monitoring and supplementation of these nutrients are also crucial.41

Congenital heart disease increases the risk of necrotising enterocolitis in full-term neonates. Possible risk factors for necrotising enterocolitis in this patient were a low cardiac output and rapid escalation of formula concentration. Preventive strategies for necrotising enterocolitis include the exclusive use of breast milk, implementation of a standardised feeding protocol and potential role of probiotics.48 49

Conclusion

We report a favourable outcome in medical management and demonstrate the decision-making process for treatment in MA. Echocardiography is an effective modality in identifying this anomaly. The initial medical management of MA focuses on controlling CHF resulting from MV insufficiency. Post-capillary pulmonary hypertension can occur because of an elevation in LA pressure. Complications, such as airway compression, atrial fibrillation and thrombus formation, should be monitored, particularly in cases of marked LA enlargement. Surgical decision-making should be considered when severe CHF is refractory to medical therapy. The choice of surgical options depends on the experience of the specific institute. The involvement of a holistic treatment team is crucial in providing comprehensive care for MA.

Learning points

  • In mitral arcade, the initial medical management focuses on controlling congestive heart failure (CHF) due to mitral valve insufficiency.

  • Complications, such as airway compression, atrial fibrillation and thrombus formation should be monitored in cases of considerable left atrial enlargement.

  • Surgery should be considered for refractory severe CHF, and surgical options depend on the institute’s experience.

  • Optimal growth assessment and nutritional support are crucial for preventing growth failure and enhancing short and long-term outcomes.

Ethics statements

Patient consent for publication

References

Footnotes

  • Contributors The following authors were responsible for drafting of the text, sourcing and editing of clinical images, investigation results, drawing original diagrams and algorithms, and critical revision for important intellectual content: TT, NB and SE. The following authors gave final approval of the manuscript: TT, NB and SE.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.